U.S. Pat. Nos. 3,909,241 and 3,974,245, and a publication by R. F. Cheney entitled "Plasma Melted Rapidly Solidified Powders" in "Plasma Processing and Synthesis of Materials", Eds. J. Szekely and D. Apelian Elsevier Science Publishing Co., N.Y. 1984, pp. 163-167, relate to processes for producing free flowing powders by agglomerating finely divided material, classifying the agglomerates to obtain a desired size range, entraining the agglomerates in a carrier gas, feeding the agglomerates through a high temperature plasma reactor to cause at least partial melting of the particles, and collecting the particles in a cooling chamber containing a protective gaseous atmosphere, wherein particles are solidified.
In accordance with the methods described in the above mentioned literature, the agglomerates are injected into a hot plasma jet using a carrier gas. The metallic particulates in the agglomerates are melted and coalesce together. However, aluminum metal alloy particulates generally have tough oxide surface layers which hinder the coalescence of these particulates even though the metals are in a molten state. Temperatures higher than the melting point of the alloys are required to break the above mentioned oxide layers so as to cause the molten particulates to coalesce together.